In 2013, the Song edition Quatrains by Tang Poets was sold at an astronomical price by Isseido Booksellers in Jimbocho of Japan. Quatrains by Tang Poets, also named as Ten Thousand Quatrains by Tang poets is a collection of poems edited by Hong Mai in the Song Dynasty. During various dynasties, the scholars had both positive and negative comments on it. On the one hand, this collection had collected a lot of Tang poems; on the other hand, there were also many errors in it, such as the wrong collection, the repeated collection and so on. This paper mainly focuses on five-character quatrains and exploring in four aspects where those problems lie; that is, mistakes in dynasties, mistakes in poets, errors in styles and the repeated collection. It also briefly analyses the causes for errors. Thus, the author hopes to evaluate its documental significance objectively and rationally.